This invention relates to a liquid dispensing valve for controlling the flow of a liquid from a container into a receptacle and, more particularly, to such a valve which automatically shuts off flow when the receptacle is full while otherwise providing full liquid flow in an audible manner.
Liquid dispensing valves designed to automatically shut off, i.e., discontinue dispensing the liquid, when a receptacle into which the liquid is being dispensed is full, are already known. Such valves typically have separate air and liquid passages. The purpose of the air passage is to allow air to enter the container to replace liquid which flows therefrom. Structure of the dispensing valve defining the air passage extends into the receptacle interior during flow of liquid from the container. When the liquid within the receptacle reaches a predetermined height (the receptacle is filled), it covers the air passage inlet and, hence, blocks the flow of air into the container. This stops liquid flow ("turns off the valve") since when no inward air flow is allowed to prevent the creation of a vacuum in the container, the liquid cannot flow therefrom. For example, such an arrangement is shown in U.S. Pat. No. 577,784 issued to C. W. and R. E. Proctor.
Prior designs of liquid dispensing valves having such an automatic shutoff arrangement have technical deficiencies which have inhibited significant adoption of the same. For one, most of such arrangements have a relatively restricted liquid flow passage so that when the air flow passage is blocked as described, no substantial air flow can enter the container through the liquid passage. This reduces the rate at which liquid can be dispensed from the container. Also, because of the separate air and liquid passages, there is no "gurgle" or other audible sound to indicate whether or not liquid is flowing from the container, i.e., there is no reverse air flow through the liquid spout which audibly interacts with such liquid. In view of this, it is difficult for a user of such an arrangement to easily tell whether or not liquid is flowing from the container. Thus, the user cannot reliably tell when a receptacle is full so that he can discontinue the filling operation. This deficiency is particularly noticeable if the receiving receptacle has a relatively small mouth, such as found on fuel tanks, not conducive to a visible checking of the liquid depth.